The pelleting of food materials from various ingredients is well known in the art and the inventor herein is also the inventor of several different controllers which have revolutionized the pelleting process by automating pelleting. Some of the patents which have issued for his devices include the following: U.S. Pat. Nos. 3,707,978; 3,932,736; 4,340,937; 4,342,361; 4,463,430; and other patent applications which are pending.
It is well known in the art of pelleting that it is desirable to add fat into the finished pellet in controlled amounts. Generally, this is done by spraying hot liquid fat onto the pellets at some point after they have been formed and given an opportunity to dry. An example of this is shown in U.S. Pat. No. 3,101,040 issued Aug. 20, 1963. As shown therein, a special rotating drum is utilized to stir the pellets and a pipe with several nozzles extends the length of the drum and sprays hot fat onto the finished pellets. There are several disadvantages with the apparatus and method of the referenced patent, including the tendency of the fat to coat the surface of the pellet and not penetrate into the substance of the pellet itself which not only renders the fat coating subject to being removed by handling of the pellets, but also limits the amount of fat that can be added without introducing the problems of stickiness and congealing of the coating which is undesirable. Furthermore, the pipe and sprayers conducting the liquid fat are subject to clogging during use which detracts from the efficiency of the apparatus in coating the pellets with fat.
To solve these and other problems, the inventor herein has succeeded in developing a novel apparatus and method of utilizing steam as a carrier for the liquid fat, and also spraying the pellets immediately as they are formed within the chamber containing the pelleting die and rollers. With this approach, the fat has a greater tendency to migrate into the substance of the pellet both because of the increased moisture content of the pellet itself and the additional moisture and energy added by the steam. Thus, a greater amount of fat may be added to the pellets. Furthermore, there is no requirement for an additional rotating drum or other mechanical structure to achieve the application of fat to the pellets which minimizes initial cost for the equipment as well as decreased maintenance expenses and the like. In implementing the inventor's new apparatus and method for achieving fat injection with steam in the pellet mill, he has also developed a related control system which provides a method for regulating the amount of fat injected into the system, and also a way of utilizing steam to blow out the fat supply lines at the end of a run to minimize any tendency of the lines to clog, even temporarily, as might be experienced with the apparatus of the prior art.
A separate fat injection controller can be provided to control the various valves utilized to regulate and control the flow of fat and steam to the pellet mill, or the control for the fat injection system of the present invention may be incorporated into one of the inventor's prior automatic pelleting control systems using techniques well known to those of ordinary skill in the art. For example, for a microprocessor based controller, it would be a simple matter for one of ordinary skill in the art to modify the software program resident therein to control the additional functions required for fat injection using the inventor's apparatus and method disclosed and claimed herein.
The foregoing represents a brief description of some of the principal advantages and features of the present invention. A more complete understanding may be gained by referring to the drawing and description of the preferred embodiment which follows.